Abstract
We describe a new species of spiny Solanum (Solanumsubg.Leptostemonum), endemic to the Brazilian Atlantic Forest and associated with granitic outcrops (inselbergs or sugar loaf mountains). Solanumkollastrum Gouvêa & Giacomin, sp. nov. is morphologically similar to the poorly known S.sublentum Hiern, but is a heavily armed, much more robust plant with stellate-glandular indumentum. Together with S.sublentum, it is morphologically related to some species of Solanum such as S.hexandrum Vell., S.robustum H.Wendl., and S.stagnale Moric. that share strongly accrescent calyces, large leaves with the bases decurrent on to the petiole, pendent simple inflorescences and large, robust flowers. The new species is restricted to a few known populations in southern Bahia and north-eastern Minas Gerais states and conservation efforts are needed.